One powerfully communicative aspect of language is prosody, which is the use of pitch, loudness, local rate modulation, and pauses in speech to signal its informational and affective content. Speech production deficits due to neurological damage such as stroke or due to Autism Spectrum Disorder are often characterized by prosodic irregularities. The long term objective of the proposed research program is to understand how linguistic structure and communicative context condition the spatiotemporal realization of articulatory movement during speaking. Our linguist-engineer team studies the signatures of prosody at the level of articulatory patterning. The specific aims of this proposal are to understand and model how speakers differentially modulate the spatiotemporal organization of articulatory gestures as a function of the cognitive source of a break in the speech stream and how the communicative context influences the temporal flow of the speech stream in articulation as speakers interact with one another. We outline a research strategy that investigates the relation between speech initiation/cessation and the control and coordination of articulation. Speech may start, pause, or cease for a variety of reasons in addition to linguistically structured phrase edges. Some breaks in the speech stream may be cognitively planned, such as interlocutor turn-taking in discourse. Other disruptions in the speech stream might be unplanned, such as interruptions and word finding challenges. Our approach investigates the articulation of speech in the vocal tract at turn-taking and interruptions in structured dialogue and in the vicinity of pauses that occur for cognitive speech planning reasons. We complement this experimental work with computational modeling of phrasal junctures and pauses, and with machine learning approaches to classifying breaks in speech arising from differing sources. The specific aims will be pursued by using articulatory movement data collected with magnetometer systems for tracking movement inside the mouth and by using our team's computational model of speech production. The experiment work and the concomitant computational modeling of the articulatory findings will provide a profile of the manner in which articulatory patterning is shapd by the larger informational structuring of utterances and by the demands of speech planning in a communicative context.